How to Get Client IP Address in PHP

You can simply use:

<?php 
echo $_SERVER['REMOTE_ADDR'];
?>

Or you can use detailed script below:

<?php
//Mainly, $_SERVER['REMOTE_ADDR'] contains IP address of client who viewing the page
function get_client_ip($single = 2) {
    $ipaddress = array();
    if( $single == 2){
      if (isset($_SERVER['HTTP_CLIENT_IP']))
          $ipaddress[] = $_SERVER['HTTP_CLIENT_IP'];
      if(isset($_SERVER['HTTP_X_FORWARDED_FOR']))
          $ipaddress[] = $_SERVER['HTTP_X_FORWARDED_FOR'];
      if(isset($_SERVER['HTTP_X_FORWARDED']))
          $ipaddress[] = $_SERVER['HTTP_X_FORWARDED'];
      if(isset($_SERVER['HTTP_FORWARDED_FOR']))
          $ipaddress[] = $_SERVER['HTTP_FORWARDED_FOR'];
      if(isset($_SERVER['HTTP_FORWARDED']))
          $ipaddress[] = $_SERVER['HTTP_FORWARDED'];
      if(isset($_SERVER['REMOTE_ADDR']))
          $ipaddress[] = $_SERVER['REMOTE_ADDR'];
      if(count($ipaddress) == 0)
          $ipaddress[] = 'UNKNOWN';
      $ips = implode(", ", array_unique($ipaddress));
    }
    if( $single == 1){
      $ips = $_SERVER['REMOTE_ADDR'];
    }
    return $ips;
}
?>